There is a plurality of surgical techniques for treating eye lens clouding, which is denoted in medicine as a cataract. The most widespread technique is phacoemulsification, in which a thin needle is introduced into the eye lens and excited to vibrate by means of ultrasound. In its direct vicinity, the vibrating needle emulsifies the lens in such a way that the resulting lens particles can be suctioned away through a line by means of a pump. A rinsing fluid (irrigation fluid) is supplied in the process, the particles and the fluid being suctioned away through an aspiration line which is usually arranged inside the needle. Once the lens has been completely emulsified and removed, a new, artificial lens can be inserted into the empty capsular bag so that a patient being treated in such a way can regain good visual acuity.
A cataract surgical procedure is an intervention with relatively low complication rate and large patient numbers. However, the relatively low complication rate can be achieved only when a highly experienced surgeon carries out the surgical procedure. When the eye lens is being comminuted by a needle tip vibrating with ultrasound, during the surgery a relatively large particle is unavoidably placed in front of a needle tip such that a needle tip and/or its suction opening is blocked. This state is denoted as occlusion. In such a case, the suction pressure inside the aspiration line rises sharply, emulsification being interrupted at this time. The fluid and the small particles can be suctioned off usually only when, for example owing to a very high input of energy, a sharp increase in suction pressure or to a reversal of the aspiration pump running direction, the particle is once again removed from the needle tip. It follows that a stoppage is broken up at such a time, there being a sudden decrease in the previously applied high vacuum. The suction thus resulting can have the effect that not only small particles and fluid are sucked toward the aspiration needle, but also that a part of the capsular bag comes into contact with the needle. When the capsular bag is penetrated, this leads to substantial complications for the patient which must be avoided unconditionally. When an occlusion is imminent, an experienced operator has developed over time a knack of breaking it up. Nevertheless, a risk always remains that the patient's eye could be damaged.